Systems and methods for reducing energy consumption in production of ethanol fuel by conversion to hydrocarbon fuels

ABSTRACT

Systems and methods are presented that reduce energy and water consumption in processes for producing fuel from renewable alcohol-containing feedstreams. Alcohol content is converted directly to hydrocarbon transport fuels in a catalytic process, with heat transferred between intermediate process streams to reduce heat energy consumption. Overall water consumption is reduced by recovery of water from the catalytic process and reduction of water temperature to reduce evaporative losses.

This application claims the benefit of U.S. Provisional PatentApplication No. 62/184,142, filed Jun. 24, 2015 and U.S. ProvisionalPatent Application No. 62/174,672, filed Jun. 12, 2015. These and allother referenced extrinsic materials are incorporated herein byreference in their entirety. Where a definition or use of a term in areference that is incorporated by reference is inconsistent or contraryto the definition of that term provided herein, the definition of thatterm provided herein is deemed to be controlling.

FIELD OF THE INVENTION

The field of the invention is the conversion of alcohol from renewablesources into hydrocarbon fuels.

BACKGROUND

The background description includes information that may be useful inunderstanding the present invention. It is not an admission that any ofthe information provided herein is prior art or relevant to thepresently claimed invention, or that any publication specifically orimplicitly referenced is prior art.

Ethanol is currently receiving a great deal of interest as a renewablesource of alternative transport fuel, with over 23 billion gallons (87billion liters) of ethanol produced for fuel purposes in 2014 worldwide.Ethanol is typically derived via a fermentation process (for example,corn ethanol fermentations) and then concentrated via distillation andmolecular sieves to produce a fuel grade product. Unfortunately, theformation of ethanol/water azeotropes for which the composition of theliquid and vapor are identical complicates recovery of high purityethanol. As a result, removal of ethanol from fermentation broths toproduce high purity ethanol suitable for use as a fuel or in fuelmixtures frequently requires processing through energy-intensivedistillation steps that include application of energy-intensiveprocesses that specifically remove water from azeotropic mixtures. Theseadditional steps significantly impact the costs of producing fuel-gradeethanol, lower potential greenhouse gas reductions, and cast doubts onthe sustainability of ethanol as a renewable fuel.

There are a number of shortcomings to the use of ethanol as a fuel. Forexample, significant adaptation of internal combustion engines isnecessary to permit them to use ethanol as a fuel. Another factor isthat ethanol is not truly fungible with conventional hydrocarbon fuels.For example, current infrastructures do not support transportation ofethanol via pipelines, but rather using tanker trucks and trains.Ethanol also has two-thirds the energy density of gasoline, whichresults in up to 50% more ethanol being needed to travel the samedistance as gasoline. Because of differences in the properties ofgasoline and ethanol most current vehicles are not warranted to useethanol/gasoline blends containing more than 10% ethanol, while theexisting infrastructure is limited to using up to 85% ethanol ingasoline (i.e. E85 fuel blend). The lower energy density and hygroscopicnature of ethanol prevent its use in aircraft that look to maximizeenergy content per mass of fuel and minimize water retention in thefuel. In addition, ethanol is not well suited for use in diesel enginesin heavy-duty vehicles.

In addition to providing low energy density, production of fuel-gradeethanol from renewable sources (such as fermentation products) hasrelatively high energy requirements. Ethanol feedstocks provided fromrenewable sources typically has a high water content, which must beremoved prior to use as fuel. At large scales this is typically achievedusing one or more distillation processes, which have significant heatrequirements. The limitations of ethanol distillation due to theformation of ethanol:water azeotropes necessitate the use of additionalsteps, such as the application of molecular sieves, to produce ethanolthat is sufficiently anhydrous for fuel use. The regeneration of suchmolecular sieve materials constitutes an additional energy expenditure.

In addition to high energy costs the production of fuel grade ethanolfrom renewable sources also consumes considerable fresh water. Whileapproximately 96% of the corn currently used for ethanol production isgrown without irrigation (see Aden, A. “Water Usage for Current andFuture Ethanol Production”, Southwest Hydrology, September/October 2007,pp: 22-23) and ethanol plants generally recover much of their processingwater, significant water consumption occurs in boiler systems andcooling towers. Estimates are that between 3 and 4 gallons of water areconsumed for every gallon of ethanol produced from fermentation of corn.All publications identified herein are incorporated by reference to thesame extent as if each individual publication or patent application werespecifically and individually indicated to be incorporated by reference.Where a definition or use of a term in an incorporated reference isinconsistent or contrary to the definition of that term provided herein,the definition of that term provided herein applies and the definitionof that term in the reference does not apply. Water consumption isgreater in biochemical conversion of cellulosic feedstocks to ethanol,averaging approximately 6 gallons of water for every gallon of ethanolproduced. Water consumption for thermochemical conversion of cellulosicbiomass to ethanol averages 1.9 gallons of water per gallon of ethanol.Most of this fresh water is sourced from groundwater.

Thus, there remains a need for systems and methods that reduce theenergy and water requirements of processes producing alcohol fuels fromthe output of fermentation processes.

SUMMARY OF THE INVENTION

The inventive subject matter provides apparatus, systems and methods inwhich energy and water requirements of a plant producing fuel from analcohol-containing feedstream are reduced. The alcohol-containingfeedstream is directed through a catalytic process that produces energydense hydrocarbon fuels. Energy requirements are reduced or eliminatedby transferring heat between intermediate process and/or product streamsand by combustion of light hydrocarbon products. Water requirements arereduced by recovery of water generated by the catalytic process andcooling of water streams to reduce evaporation.

One embodiment of the inventive concept is a method for producing ahydrocarbon product. In such a method an alcohol broth is supplied to aprimary beer column pre-heater (and in some instances a second beercolumn pre-heater) to generate a heated alcohol broth, which istransferred to a beer column. The beer column produces a firstintermediate product stream (which includes an alcohol/water mixture)and a second intermediate product stream (which includes residual solidmatter). The first intermediate product stream is directed to a reactorpre-heater to produce a pre-heated first intermediate product streamhaving a temperature of at least about 220° C. In some embodiment all orpart of the second intermediate product stream is returned to the beercolumn. The pre-heated first intermediate product stream is directed toa furnace to produce a heated first intermediate product stream having atemperature of at least about 250° C. The heated first intermediateproduct stream is directed to a catalytic reactor, which generates athird intermediate product stream that includes a hydrocarbon product,water and a light hydrocarbon. This third intermediate product stream isdirected to a phase separator along a heat transfer route, which isarranged to transfer at least a portion of heat energy of the thirdintermediate product stream to the reactor pre-heater and/or the primarybeer column pre-heater. The phase separator separates the thirdintermediate product stream into a hydrocarbon product (which iscollected and includes the hydrocarbon product), a water stream, and alight hydrocarbon fraction stream. In some embodiments the lighthydrocarbon fraction stream is transferred to the furnace for use as afuel, which can be replaced or supplemented by natural gas. In someembodiments the water stream is used in a fermentation process. Thehydrocarbon product can be gasoline, diesel fuel, jet fuel, chemicals,or a BTX product. In such embodiments the energy supplied to the methodin the production of a volume of the hydrocarbon product represents lessthan 20% of energy obtained by combustion of the volume of thehydrocarbon product.

Another embodiment of the inventive concept is a system for carrying outthe method described above. Such a system includes a source of alcoholbroth which is in fluidically connected to a primary beer columnpre-heater (which can, in turn, be connected to a second beer columnpre-heater). The system also includes a beer column that receives aheated ethanol broth from the primary beer column pre-heater andproduces a first intermediate product stream (which includes analcohol/water mixture) and a second intermediate product stream (whichincludes residual solid matter). The system also includes a reactorpre-heater that is fluidically connected to the beer column and thatreceives the first intermediate product stream, heating it to produce apre-heated first intermediate product stream. The system also includes afurnace that is fluidically connected with the reactor pre-heater andthat receives the pre-heated first intermediate product stream, heatingit to at least about 250° C. to produce a heated first intermediateproduct stream. The system also includes a catalytic reactor that isfluidically connected to the furnace and that generate a thirdintermediate product stream, which includes a hydrocarbon product,water, and a light hydrocarbon. Such a system also includes a firstconduit that is positioned to direct the third intermediate productstream to a phase separator, and to transfer at least some of the heatenergy of the third intermediate product stream to the reactorpre-heater (and, in some embodiments, the primary beer columnpre-heater). The phase separator separates the third intermediateproduct stream into a hydrocarbon product stream (which includes ahydrocarbon product), a water stream (which can be directed to afermentation process), and a light hydrocarbon fraction stream. Thehydrocarbon product can be gasoline, diesel fuel, jet fuel, chemicals,and/or a BTX product. In some embodiments the system includes a secondconduit that is fluidically connected to the phase separator andpositioned to direct the light hydrocarbon fraction stream to thefurnace. In other embodiments this can be replaced or supplemented by asource of natural gas. In some embodiments the system includes a thirdconduit that is fluidically connected to the beer column, and ispositioned to direct at least part of the second intermediate processstream back to the beer column. In some embodiments the energy suppliedto the system to produce a given volume of the hydrocarbon productrepresents less than 20% of energy obtained on combustion of the volumeof hydrocarbon product.

Another embodiment of the inventive concept is a method for reducingwater consumption in a fuel plant. In such a method an alcohol broth(which includes an alcohol is obtained and transferred to a primary beercolumn pre-heater (and in some embodiments to an additional secondarybeer column pre-heater), where it is heated to produce a heated alcoholbroth. The heated alcohol broth is transferred from the primary beercolumn pre-heater to a beer column , which generates a firstintermediate product stream (which includes a concentrated alcohol/watermixture). The concentrated alcohol/water mixture is transferred to acatalytic unit pre-heater, which generates a pre-heated alcohol/watermixture. The pre-heated alcohol/water mixture is transferred to an oven,which generates a heated alcohol/water mixture. The heated alcohol/watermixture is transferred to a catalytic unit, which generates a secondintermediate product stream that includes water and a hydrocarbonproduct (and, in some embodiments, a light hydrocarbon). In someembodiments this catalytic step generates at least one mole of water forevery mole of alcohol that is converted into hydrocarbons. The secondintermediate product stream is transferred to a phase separator, whichseparates it into a hot water stream and a hydrocarbon product stream(and, in some embodiments, a light hydrocarbon stream). The hot waterstream is then recycled into either or both of a fermentation process ora fuel generating process. In some embodiments heat from the hot waterstream can be transferred to the secondary beer column pre-heater, whichcan be supplemented with heat transferred from the second intermediateproduct. Such heat transfer processes can reduce the temperature of thehot water stream. In some embodiments of the inventive concept the hotwater stream is cooled (for example by at least 30° C.) to produce acooled water stream. This cooling can be accomplished using a passivedevice (such as a radiator) or an active device (such as an absorptioncooler). In some embodiment such an active device can be powered by heatthat is transferred from the second intermediate product stream. In someembodiments, the light hydrocarbon stream can be utilized as fuel forthe furnace.

Another embodiment of the inventive concept is a system for reducingwater consumption in a fuel plant. Such a system includes a source of analcohol broth comprising ethanol and a primary beer column pre-heaterthat is fluidically connected to the source of alcohol broth, and insome embodiments a secondary beer column pre-heater that is fluidicallyconnected to this primary beer column pre-heater. The system alsoincludes a beer column that is fluidically connected to the primary beercolumn pre-heater, and which produces a first intermediate productstream that includes a concentrated alcohol/water mixture. The systemalso includes a catalytic unit pre-heater that is fluidically connectedto the beer column, and that receives the concentrated alcohol/watermixture to produce a pre-heated alcohol/water mixture. The system alsoincludes an oven that is fluidically connected to the catalytic unitpre-heater, which receives the pre-heated alcohol/water mixture andproduces a heated alcohol/water mixture. The system also includes acatalytic unit that is fluidically connected to the oven, and which andthat receives the heated alcohol/water mixture and produces a secondintermediate product stream which includes water and a hydrocarbonproduct (and, in some embodiments, light hydrocarbons). Such a catalyticunit can produce at least 1 mole of water for every mole of alcohol thatis converted to hydrocarbon product. The system also includes a phaseseparator that is fluidically connected to the catalytic unit and thatreceives the second intermediate product stream, and which separate thesecond intermediate product stream into a hot water stream, ahydrocarbon product stream, and (in some embodiments) a lighthydrocarbon stream. Such a system includes a first conduit that isfluidically connected to the phase separator and which carries the hotwater stream for recycling. Such a first conduit can be positioned totransfer heat from the hot water stream to a beer column pre-heater (forexample, a secondary beer column pre-heater). In some embodiments thesystem includes a cooling unit that is fluidically connected to thefirst conduit and that provides a cooled water stream. Such a coolingunit can be a passive device (such as a radiator) or an active device(such as an absorption cooler). In some embodiments the system includesa second conduit that is fluidically connected to the catalytic reactorand to the phase separator, and which serves to transfer the secondintermediate product from the catalytic reactor to the phase separatorwhile transferring at least part of the heat contained in the secondintermediate product to such an active cooling device. In someembodiments the system includes a third conduit that is fluidicallyconnected to the phase separator and to the oven, and which serves totransfer the light hydrocarbon stream from the phase separator to theoven. In some embodiments the system includes a fourth conduit that isfluidically connected to the catalytic unit and the phase separator andthat receives the second intermediate product stream from the catalyticunit. In such an embodiment the fourth conduit is positioned to transferheat energy contained in the second intermediate product stream to abeer column pre-heater (such as the secondary beer column pre-heater).

Various objects, features, aspects and advantages of the inventivesubject matter will become more apparent from the following detaileddescription of preferred embodiments, along with the accompanyingdrawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically depicts a typical prior art process for dry millproduction of alcohol fuel via grain fermentation.

FIG. 2 schematically depicts an exemplary process of the inventiveconcept, in which a fermentation process (for example, production ofethanol via grain fermentation) is coupled to a catalytic process toconvert ethanol to hydrocarbons, showing transfer of heat betweenvarious individual processes.

FIG. 3 schematically depicts another exemplary system of the inventiveconcept, in which a fermentation process (for example, production ofethanol via grain fermentation) is coupled to a catalytic process toconvert alcohol to hydrocarbons, showing cooling and recycling of waterproduced in the catalytic process.

FIG. 4 schematically depicts another exemplary system of the inventiveconcept, in which a fermentation process (for example, production ofethanol via grain fermentation) is coupled to a catalytic process toconvert alcohol to hydrocarbons.

DETAILED DESCRIPTION

The following description includes information that may be useful inunderstanding the present invention. It is not an admission that any ofthe information provided herein is prior art or relevant to thepresently claimed invention, or that any publication specifically orimplicitly referenced is prior art.

The inventive subject matter provides apparatus, systems and methods inwhich an alcohol/water vapor mixture, for example a mixture obtainedfrom a location downstream of a fermentation process (e.g., as afeedstream from a beer column, rectification column, molecular sieves),is catalytically reacted to produce hydrocarbon products and water. Thecatalytic process converts at least a portion of the ethanol of such analcohol/water vapor mixture into a mixture that includes hydrocarbonfuels and/or other chemicals such as BTX (benzene, toluene, and/orxylene) and water, from which the targeted products are readilyseparated from water and/or any gaseous byproducts (for example, lighthydrocarbons derived from ethanol). Exemplary reactions of this processfor various alcohols are shown below in Formulas 1 to 4, where —C₂H₄—represents a hydrocarbon (for example, hydrocarbons of a hydrocarbonfuel).2CH₃OH→—C₂H₄—+2H₂O (Conversion of methanol to hydrocarbons andwater)  Formula 1C₂H₅OH→—C₂H₄—+H₂O (Conversion of ethanol to hydrocarbons andwater)  Formula 22C₃H₇OH→3-C₂H₄—+2H₂O (Conversion of propanol to hydrocarbons andwater)  Formula 3C₄H₉OH→2-C₂H₄—+H₂O (Conversion of butanol to hydrocarbons andwater)  Formula 4Water recovered from this reaction can be re-utilized to reduce waterlosses associated with corn or cellulosic ethanol production facilities(for example, evaporative losses in cooling tower, solids drying, boilersystem, etc.) and/or reutilized in feedstock irrigation. In addition,heat provided by combustion of light hydrocarbon products of thecatalytic reaction and heat generated by the ethanol conversion processcan be transferred to and utilized in ethanol production and recoveryprocesses (for example, in beer column and/or rectification columnreboilers) to reduce energy costs in a more carbon-neutral manner.

Heat provided by combustion of light hydrocarbon products of thecatalytic reaction and heat generated in the ethanol conversion processare transferred to and utilized in various processes of the plant,thereby reducing energy costs in a carbon-neutral manner.

In some embodiments, the numbers expressing quantities of ingredients,properties such as concentration, reaction conditions, and so forth,used to describe and claim certain embodiments of the invention are tobe understood as being modified in some instances by the term “about.”Accordingly, in some embodiments, the numerical parameters set forth inthe written description and attached claims are approximations that canvary depending upon the desired properties sought to be obtained by aparticular embodiment. In some embodiments, the numerical parametersshould be construed in light of the number of reported significantdigits and by applying ordinary rounding techniques. Notwithstandingthat the numerical ranges and parameters setting forth the broad scopeof some embodiments of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspracticable. The numerical values presented in some embodiments of theinvention may contain certain errors necessarily resulting from thestandard deviation found in their respective testing measurements.

One should appreciate that the disclosed systems and methods providemany advantageous technical effects including providing a continuousprocess for conversion of corn, sugar, or lignocellulose-derivedalcohols to high energy density transportation fuels and/or BTX productswhile providing reduced costs, power consumption, water consumption, andcarbon footprint.

As used herein, and unless the context dictates otherwise, the term“coupled to” is intended to include both direct coupling (in which twoelements that are coupled to each other contact each other) and indirectcoupling (in which at least one additional element is located betweenthe two elements). Therefore, the terms “coupled to” and “coupled with”are used synonymously.

Production of fuel from grain sources, for example corn, generallybegins with fermentation and provides such fuel in the form of analcohol (e.g., ethanol, propanol, and/or butanol,). A workflow for atypical prior art process is shown below in FIG. 1.

FIG. 1 schematically illustrates a typical prior art grain dry millfermentation to ethanol fuel process, an ethanol broth exitingfermentation is first heated in a beer column pre-heater 105 throughheat exchange with the bottoms stream from the beer column 115. Afterthis heat exchange, solids from this bottoms stream are removed (forexample by centrifugation or filtration), dried, and sold as drieddistillers grains (DDGs). In some prior art processes a supplementalheater 110 is used to further increase the temperature of the ethanolbroth. The pre-heated ethanol broth is then transferred to a beer column115, where ethanol is stripped from the ethanol broth to create aconcentrated ethanol/water mixture that typically contains 40-60%ethanol (w/w). This transfer of heat from the bottoms stream to the beercolumn pre-heater 105 lowers process heating/energy requirements by heatintegration. The ethanol/water vapor mixture from the beer column istransferred to a rectification column 120, where distillation of theethanol/water mixture (typically ˜40-60% alcohol (w/w) on entry to therectification column) provides further separation of ethanol from thewater mixture and produces a high ethanol content fraction. The highethanol content fraction is subsequently passed through molecular sieves125 to generate high purity ethanol that can be used as a transport fuel(albeit, one with lower energy density compared to conventionalgasoline). The bottoms stream from the rectification column (having alow percent ethanol content) is transferred to a stripper 130, whichseparates most of the remaining ethanol and returns it to therectification column 120 for additional processing. Water from thestripper 130 can be recycled for use in fermentation and otherprocesses.

It should be appreciated that energy consumption by various componentsof such a system are significant. For a typical plant, the energyconsumption per gallon of fuel ethanol produced is as follows: beercolumn pre-heater ˜3,000 BTU, beer column ˜20,000 BTU, rectificationcolumn ˜7,000 BTU, molecular sieve ˜2,000 BTU, and stripper ˜1,000 BTU.This energy can be provided by burning fossil fuels (such as naturalgas), which negatively impacts the carbon footprint of this process.Alternatively, such steps could be fueled using a portion of the ethanolproduct, but at the cost of process efficiency.

It should be noted that the ˜33,000 BTU that are utilized to produce onegallon of ethanol fuel represent over 40% of the energy produced bycombustion of the ethanol. When such real world factors such asevaporative losses, transportation costs (which are elevated for lowenergy density fuels such as ethanol), and less than perfectcombustion/energy transfer efficiency are factored in the costs ofproducing ethanol fuel from such processes become significant. With suchhigh energy requirements the actual sustainability of ethanol as a fuelusing such processes becomes subject to debate.

In processes of the inventive concept, a catalytic reactor is coupled toconventional alcohol separation process to generate fungible (i.e.interchangeable with petrochemical) transport fuels (such as diesel,gasoline, or jet fuels), in at least some embodiments along with gaseouslight hydrocarbon products, from alcohol and water mixtures. Such acatalytic process can also be utilized to generate other chemicals suchas benzene, toluene, and/or xylene products (i.e., BTX), along withother hydrocarbon fractions. The catalytic process utilizes elevatedtemperatures, and heat from reactor effluent can be heat integrated withseveral intermediate process streams to reduce overall plant heatrequirements, GHG emission, and the use of fossil derived fuels.

It should be appreciated that while examples are provided in the contextof conversion of ethanol provided by fermentation, other alcoholfeedstocks can also be used. For example, methanol obtained frompyrolysis of lignocellulosic material and/or from synthesis gasgenerated from renewable sources (e.g. biomass) can be utilized as afeedstock in systems and methods of the inventive concept. Similarly,propanol and/or butanol derived from renewable sources, for examplethrough the use of genetically modified microorganisms, can be used. Insome embodiments two or more alcohol feedstocks can be combined prior toor on entry into systems and methods of the inventive concept. In suchembodiments the combined alcohol feedstocks need not be of the sametype. For example, an ethanol feedstock derived from grain fermentationcan be combined with a methanol feedstock produced from synthesis gasderived from biomass. It should be appreciated that this capacityprovides systems and methods of the inventive concept with processflexibility not present in the prior art. An example of a process of theinventive concept is shown in FIG. 2.

Unless the context dictates the contrary, all ranges set forth hereinshould be interpreted as being inclusive of their endpoints, andopen-ended ranges should be interpreted to include only commerciallypractical values. Similarly, all lists of values should be considered asinclusive of intermediate values unless the context indicates thecontrary. The recitation of ranges of values herein is merely intendedto serve as a shorthand method of referring individually to eachseparate value falling within the range. Unless otherwise indicatedherein, each individual value with a range is incorporated into thespecification as if it were individually recited herein.

FIG. 2 schematically depicts an embodiment of a system of the inventiveconcept in which an alcohol production facility is coupled with acatalytic reactor, fermentation broth enters the process and is firstheated, by a first beer column pre-heater 205. Such a fermentation brothcan be an ethanol broth, however it should be appreciated that thefermentation broth can be an alcohol broth that includes methanol,ethanol, propanol, butanol, or a mixture of two or more of these. Atleast some of the heat for this process can be provided by the beercolumn 215 bottoms stream (which includes water and residual solids). Atthis point in the process solids can be removed from such a bottomsstream by any suitable method and be further processed (for example, asDDGs in corn ethanol production and/or solids for use as boiler fuel incellulosic ethanol plants). Suitable methods for separation of thesesolids include decantation, settling, filtration, and centrifugation. Ina preferred embodiment of the inventive concept solids are removed fromthe bottoms stream by a centrifuge or vortex device that permitscontinuous removal of solids from the bottoms stream.

The pre-heated alcohol broth can be transferred to a second beer columnpre-heater 210 where it is further heated (for example, via heatexchange with a product stream from a catalytic reactor 230). In someembodiments of the inventive concept, a single beer column pre-heatercan be utilized, and can receive heat from either of both of the bottomsstream from the beer column 215 and a product stream from the catalyticreactor 230. This heated alcohol broth can then be directed into a beercolumn 215, where alcohol (i.e. methanol, ethanol, butanol and/orpropanol) is stripped from the alcohol broth as a concentratedalcohol/water stream (for example, a vapor). Such an alcohol/waterstream can contain 10%, 20%, 30%, 40%, 50%, 60%, 70% or more alcohol byweight. In a preferred embodiment of the inventive concept such aconcentrated alcohol/water stream contains 40-60% alcohol (w/w). Asshown, bottom materials from the beer column 215 can be transferred tothe first beer column pre-heater 205 to recover heat from this stream,thus lowering heating/energy requirements (i.e. via heat integration).

In some embodiments of the inventive concept the alcohol/water mixturefrom the beer column 215 can be directed to the catalytic reactor 230without a change in composition. In other embodiments (not depicted), arectifier or similar apparatus can be utilized to provide additionalseparation of alcohol from the alcohol/water mixture obtained from thebeer column 215 to produce an alcohol -enriched alcohol/water streamthat is directed to a catalytic reactor 230. In such an embodiment, therectifier or similar apparatus would be interposed between and in fluidcommunication with the beer column 215 and the catalytic reactor 230. Ineither of such embodiments, the alcohol/water mixture can be transferredto reactor pre-heater 220, which raises the temperature of thealcohol/water mixture from about 110° C. to about 220° C. (for example,via heat exchange with a product stream of the catalytic reactor 230).Such a pre-heated alcohol/water mixture can then be transferred to afurnace 225, where it is heated to a temperature suitable for thecatalytic reaction (for example, about 275° C. to about 350° C.). Outputfrom furnace 225 is directed to a catalytic reactor 230, which producesa product stream that can include the desired fuel, BTX, or chemicalproduct, water, and/or light hydrocarbon products at about 350° C.

The elevated temperature of the catalytic reactor 230 product streamrepresents a source of considerable thermal energy that can be utilizedadvantageously before it reaches a phase separator 235 (for example, a3-phase decanter). A portion of this heat can be transferred to thealcohol/water mixture preheater 220, thereby reducing the temperature ofthe catalytic reactor product stream (for example, to about 230° C.).Similarly, a portion of the remaining heat can be transferred to thebeer column 215 (e.g. to a reboiler) and/or to a second beer columnpre-heater 210 to reduce or eliminate fuel consumption of thesecomponents, and further reduce the temperature of the catalytic reactor230 product stream (for example, to about 120° C.). Remaining heat, or aportion thereof, can be transferred to a first beer column pre-heater205, reducing or eliminating the fuel requirements for this process.

Following such heat integration steps, the product stream from thecatalytic reactor 230 mixture is transferred to a phase separator 235,which separates the mixture into two or more product streams, forexample (a) jet, diesel, gasoline, chemicals, or BTX hydrocarbonproducts that can be used directly, (b) water, which can be recycled(for example, into a fermentation process), and (c) light hydrocarbon240 fractions. Suitable phase separators include decanters (such as a3-phase decanter), centrifuges, and membrane separators. As shown, lighthydrocarbon fractions 240 can be directed to the furnace 225, wherecombustion provides heat to the alcohol/water mixture. If availablelight hydrocarbon fractions are insufficient or if the light fractionhas sufficient commercial value, additional fuel (for example, naturalgas) can be supplied to either supplement or entirely provide for thesystem's heat requirements.

As shown, the heat energy in the catalytic reactor product stream can beheat integrated with multiple components of the process in order toreduce heating requirements during the transfer of the product+watermixture to a phase separator. As shown, the hot product+water mixturecan be routed to provide heat to a reactor pre-heater, a beer column, abeer column heater, and/or a beer column pre-heater(s). Thisadvantageously provides necessary heat to these components whileeliminating or reducing the need for fuel, while at the same timecooling the product+water mixture to temperatures suitable for operationof a phase separator. Heat integration can be performed by any suitablemeans. Suitable means include heat exchanging assemblies that bring theproduct streams undergoing heat transfer into direct thermalcommunication. Alternatively heat can be transferred indirectly, forexample through the use of a heat transfer medium that is in thermalcommunication with both a heat source stream and a heat destinationstream, or through the use of a heat pipe. Alternatively, heat energycan be transformed into a different form of energy (for example,electrical power or mechanical work) at a heat source, transmitted to aheat destination, and transformed back into heat energy (for example byresistance heating or friction).

Such heat transfer, in combination with heat provided by combustion oflight fraction products of the process, can provide all or part (e.g.,about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about90%, or more) of the heat necessary to support the overall process. Inembodiments or implementations where the amount of heat provided by theproduct+water mixture leaving the catalytic reactor and combustion oflight fraction products is not sufficient, the shortfall can beaccommodated using natural gas, combustion of other suitable fuels, ortransfer of heat from other processes (for example, processes externalto the system of the inventive concept).

Due to the relative lack of fuel consuming distillation processes andtransfer of heat from the output of the catalytic reactor, considerableenergy savings are realized relative to prior art processes. For atypical plant utilizing systems and methods of the inventive concept,energy consumption per gallon of fuel produced is as follows: beercolumn pre-heater ˜3,000 BTU, beer column ˜10,000 BTU, furnace ˜2,000BTU. Overall, ˜15,000 BTU are utilized per gallon of fuel produced. Thisrepresents a greater than 50% reduction in energy costs relative toprior art processes.

It should also be appreciated that the resulting products are energydense fuels or high value organic solvents that can be utilized directlyin current vehicles and processes without adaptation. As such, theapproximately 15,000 BTU utilized per gallon of fuel produced by systemsand processes of the inventive concept represents only about 12% of theenergy contained in a gasoline or jet fuel product and about 11% of theenergy contained in a diesel fuel product. As a result, systems andmethods of the inventive concept truly enhance sustainable andeconomically viable production of fuels and/or BTX products fromrenewable sources such as grain.

Although the examples provided above focused on alcohol production fromcorn by so-called dry milling of corn, it should be appreciated thatsystems and methods of the inventive concept can be equally well appliedto production of ethanol and other alcohols (for example, methanol,propanol, and butanol) by fermentation of sugar derived from sugar caneand/or other sugar sources; fermentation of sugar released by thebreakdown of cellulosic or lignocellulosic biomass; alcohol productionfrom corn by wet-mill and other processes; and/or production of ethanolor other alcohols by non-fermentation processes (e.g., chemical orbiological mediated catalytic conversion of synthesis gas to ethanol).In some embodiments, alcohol from two or more alcohol sources can becombined and utilized in a process of the inventive concept. Such acombination can occur prior to introduction to the catalytic reactorand/or at the point of introduction to the catalytic reactor. Inaddition, it should be appreciated that the sequence and choice ofoperations can also be modified from those depicted in order to provideenergy saving benefits.

In addition to consuming large amounts of energy, it should beappreciated that typical prior art processes (such as those depicted inFIG. 1) utilize large amounts of water. Water is lost from these systemsat a number of points in the process, including: 1) evaporative lossesfrom cooling towers associated with cooling effluents from separationcolumns, 2) evaporative losses associated with drying solids (e.g.DDGs), 3) boiler blowdown to avoid concentration of impurities fromsteam evaporation, and 4) leaks. It should be appreciated that water andenergy consumption by various components of such a system can besignificant. For a typical plant utilizing corn fermentation, net waterconsumption averages between 3 and 4 gallons of water for every gallonof fuel ethanol produced. Water consumption is greater in biochemicalconversion of cellulosic feedstocks to ethanol, averaging approximately6 gallons of water for every gallon of ethanol produced. Waterconsumption for thermochemical conversion of cellulosic biomass toethanol is averages 1.9 gallons of water per gallon of ethanol.

Depending upon the starting material utilized to produce the ethanolbroth and the conversion technology, water consumption in a typicalprior art process ranges from 1.9-6 gallons of water per gallon ofethanol produced. With fresh water in increasingly short supply suchhigh water requirements the sustainability of ethanol as a fuel usingsuch prior art processes is doubtful.

As noted above, in processes of the inventive concept, a catalyticreactor can be coupled to conventional alcohol separation process togenerate fungible (i.e. interchangeable with petrochemical products)transport fuels (such as diesel, gasoline, or jet fuels) from alcoholand water mixtures. In at least some embodiments gaseous lighthydrocarbon products can additionally be produced. Such a catalyticprocess can also be utilized to generate other chemicals such asbenzene, toluene, and/or xylene products (i.e., BTX), along with otherhydrocarbon fractions (for example, light or gaseous fractions). Thecatalytic process utilizes elevated temperatures, and heat from reactoreffluent can be heat integrated with several intermediate processstreams to reduce overall plant heat requirements, GHG emission, and theuse of fossil derived fuels. Systems and methods of the inventiveconcept also significantly reduce the water requirements of fuelproduction from sustainable alcohol feedstreams. An example of a systemof the inventive concept is shown in FIG. 3.

As shown in FIG. 3, in a system of the inventive concept in which analcohol production facility is coupled with a catalytic reactor,fermentation or alcohol broth enters the process and is initiallyheated, for example in a first beer column preheater 305. Such afermentation broth can be an ethanol broth, however it should beappreciated that the fermentation or alcohol broth can include methanol,ethanol, propanol, butanol, or a mixture of two or more of these. Afterpassing through the first beer column preheater 305, the alcohol brothcan be transferred to a second beer column preheater 310 for furtherheating. At least some of the heat for these processes can betransferred from a beer column 315 bottoms stream (which typicallyincludes water and residual solids). Process solids can be removed fromsuch a bottoms stream (for example by centrifugation or filtration) andbe further processed. For example, such recovered solids can be utilizedas DDGs in corn ethanol production and/or solids for use as boiler fuelin cellulosic ethanol plants. In some embodiments of the inventiveconcept, a single beer column pre-heater can be utilized, and canreceive heat from either or both of the bottoms stream from the beercolumn 315 and a product stream from a catalytic reactor 330.

The heated alcohol broth can then be directed into a beer column 315,where alcohol (e.g. methanol, ethanol, butanol and/or propanol) isstripped from the alcohol broth as a concentrated alcohol/water stream.Such an alcohol/water stream can contain 10%, 20%, 30%, 40%, 50%, 60%,70% or more alcohol by weight. In a preferred embodiment of theinventive concept such a concentrated alcohol/water stream contains40-60% alcohol (w/w), and can be in the form of a vapor. Thealcohol/water mixture is transferred to a reactor pre-heater 320, whichraises the temperature of the ethanol/water mixture from about 110° C.to about 220° C. The pre-heated alcohol/water mixture is thentransferred to a furnace 325, where it is heated to a temperaturesuitable for the catalytic reaction (for example, about 350° C.). Outputfrom the furnace 325 is directed to the catalytic reactor 330, whichproduces the desired fuel, BTX or other chemical product mixed withwater at about 350° C.

In some embodiments of the inventive concept the alcohol/water mixturefrom the beer column 315 can be directed to the catalytic reactor 330without a change in composition. In other embodiments (not depicted), arectifier or similar apparatus can be utilized to provide additionalseparation of alcohol from the alcohol/water mixture obtained from thebeer column 315 to produce an alcohol-enriched alcohol/water stream thatis directed to a catalytic reactor 330. In such an embodiment, therectifier or similar apparatus would be interposed between and in fluidcommunication with the beer column 315 and the catalytic reactor 330. Ineither of such embodiments, the alcohol/water mixture can be transferredto reactor pre-heater 320, which raises the temperature of thealcohol/water mixture from about 110° C. to about 220° C. (for example,via heat exchange with a product stream of the catalytic reactor 330).Such a pre-heated alcohol/water mixture can then be transferred to afurnace 325, where it is heated to a temperature suitable for thecatalytic reaction (for example, about 275° C. to about 350° C.). Outputfrom furnace 325 is directed to a catalytic reactor 330, which producesa product stream that can include the desired fuel, BTX, or chemicalproduct, water, and/or light hydrocarbon 340 products at about 350° C.

The elevated temperature of the output of the catalytic reactor 330represents a source of considerable thermal energy that can be utilizedadvantageously before it reaches a phase separator 335 (for example, a3-phase decanter). A portion of this heat can be transferred to thealcohol/water mixture preheater 320, thereby reducing the temperature ofthe catalytic reactor stream (for example, to about 230° C.). Similarly,a portion of the remaining heat can be transferred to the beer column315 (e.g. to a reboiler) and/or to a second beer column pre-heater 310,rectifier reboiler, and other processes requiring heat (e.g. plant waterinput) to reduce or eliminate fuel consumption of these components, andfurther reduce the temperature of the catalytic reactor 330 productstream (for example, to about 120° C.). Remaining heat, or a portionthereof, can be transferred to the beer column pre-heater 305, reducingor eliminating the fuel requirements for this process.

Following such heat integration steps, the product stream from thecatalytic reactor 330 mixture can be transferred to a phase separator335 (for example, a 3-phase decanter), which separates the mixture intoat least three products streams: (a) jet, diesel, gasoline, chemicals,or BTX hydrocarbon products that can be used directly, (b) hot (forexample, about 80° C. to 90° C.) water, which can be recycled (forexample, into a fermentation process), and in some embodiments (c) lighthydrocarbon fractions 340. The hot water stream can be re-used as is, orit can be cooled (for example, to 40-50° C.) in order to reduceevaporative losses. Such cooling can be provided by a passive device,such as a radiator 345 or similar device. Alternatively, heat from thehot water stream can be transferred to a thermal mass during daytimeoperations, followed by cessation of heat transfer and passive coolingof the thermal mass at night. Such heat transfers can be direct (i.e.through direct thermal communication) or indirect. Indirect heattransfers can be accomplished using a heat transfer medium and/or heattransfer device (e.g. a heat pipe). In still another embodiment heat canbe transferred from the hot water stream by earth coupling. As shown,light hydrocarbon fractions 340 can be directed to the furnace 325,where combustion provides heat to the alcohol/water mixture. Ifavailable light hydrocarbon fractions are insufficient or if the lightfraction has sufficient commercial value, additional fuel (for example,natural gas) can be supplied to either supplement or entirely providefor the system's heat requirements.

As shown, the heat energy in the catalytic reactor product stream can beheat integrated with multiple components of the process in order toreduce heating requirements during the transfer of the product+watermixture to a phase separator. As shown, the hot product+water mixturecan be routed to provide heat to a reactor pre-heater, a beer column, abeer column heater/reboiler, and/or a beer column pre-heater(s). Inother embodiments, the hot product+water mixture can be used to reduceheat requirements in a rectification column. This advantageouslyprovides necessary heat to these components while eliminating orreducing the need for fuel, while at the same time cooling theproduct+water mixture to temperatures suitable for operation of a phaseseparator. Such heat transfer, in combination with heat provided bycombustion of light fraction products of the process, can provide all orpart (e.g., about 30%, about 40%, about 50%, about 60%, about 70%, about80%, about 90%, or more) of the heat necessary to support the overallprocess. In embodiments or implementations where the amount of heatprovided by the product+water mixture leaving the catalytic reactor andcombustion of light fraction products is not sufficient, the shortfallcan be accommodated using natural gas, combustion of other suitablefuels, or transfer of heat from other processes (for example, processesexternal to the system of the inventive concept).

In some embodiments of the inventive process, heat contained in the hotwater stream is transferred to other components of the system in orderto reduce energy consumption and to reduce the temperature of therecycled water (thereby reducing evaporative losses, for example fromcooling towers). An example of such an embodiment is shown schematicallyin FIG. 4.

As shown in FIG. 4, fermentation provides an alcohol broth, which can beheated in first and second beer column preheaters (405 and 410,respectively) as described above. The pre-heated alcohol broth is thentransferred to a beer column 415, where alcohol is stripped from thealcohol broth in the form of a concentrated alcohol/water mixturecontaining 10%, 20%, 30%, 40%, 50%, or more alcohol (w/w). As shown,residual materials from this process can be transferred from the bottomof the beer column to the second beer column pre-heater 410 for repeatedextraction in order to improve efficiency. As described above in thedescription of the system depicted in FIG. 3, in some embodiments asingle beer column pre-heater can be used. The concentratedalcohol/water mixture from the beer column is transferred to a reactorpre-heater 420, which raises the temperature of the alcohol/watermixture from about 110 ° C. to about 220 ° C. The pre-heatedalcohol/water mixture is then transferred to a furnace 425, where it isheated to a temperature suitable for the catalytic reaction (forexample, about 350 ° C.). Output from the furnace 425 is directed to acatalytic reactor 430, which produces the desired fuel or BTX productmixed with water (and in some embodiments, a light hydrocarbon fraction440) at about 350 ° C.

The elevated temperature of the output of the catalytic reactor 430represents a source of considerable thermal energy that can be utilizedas it is transferred to a 3-phase decanter 435. A portion of this heatcan be transferred to the reactor preheater 420, thereby reducing thetemperature of the catalytic reactor output to about 230° C. Similarly,a portion of the remaining heat can be transferred to the beer column415 and/or to the second beer column heater 410 to reduce or eliminatefuel consumption of these components, and further reduce the temperatureof the product mixture from the reactor (for example, to about 120° C.).Remaining heat, or a portion thereof, can be transferred to the firstbeer column pre-heater 405, reducing or eliminating the fuelrequirements for this process.

The output of the catalytic reactor 430 mixture can be transferred to aphase separator 435, which separates the mixture into different productsstreams: (a) a hot (for example, 80° C. to 90° C.) water stream, (b)jet, diesel, gasoline fuel products or BTX products that can be useddirectly, and, in some embodiments, (c) light hydrocarbon fractions 440.Heat from the hot water stream can be transferred to other processes inthe system in order to reduce energy costs while reducing thetemperature of the hot water stream. As shown in FIG. 4, heat can betransferred from the hot water stream to the first beer columnpre-heater 405. In some embodiments, heat transfer to other systemcomponents, radiative cooling, and/or active cooling (for example, in anabsorption cooler) can be utilized in individually or in combination toreduce the temperature of the hot water stream. Suitable active coolingmethods include use of an absorption cooler, use of an Einsteinrefrigerator, withdrawal of heat using a heat engine, and withdrawal ofheat using the thermoelectric effect. In some embodiments thetemperature of the hot water stream can be reduced by passage through anabsorption cooler 445. Such an absorption cooler 445 can be driven, atleast in part, by heat transferred from an intermediate process streamof the system. Such an embodiment is depicted in FIG. 4, in which heatfrom the output of the catalytic reactor 430 is so utilized. In otherembodiments heat from burning fuel (such as natural gas and/or lighthydrocarbon fractions 440 from the alcohol conversion process) can beused to supplement or replace heat transfer from a system process streamto the absorption cooler 445. Such treatment can reduce the temperatureof the hot water stream (for example to about 40° C. to 50° C.) andthereby reduce water losses due to evaporation. As shown, lighthydrocarbon fractions 440 can be directed to the furnace 425, wherecombustion provides heat to the alcohol/water mixture. If availablelight hydrocarbon fractions are insufficient, natural gas can beprovided as additional fuel to heat the furnace 425.

Due to the relative lack of water and fuel consuming distillationprocesses, lack of use of molecular sieves, and transfer of heat fromvarious process streams, considerable water and energy savings arerealized relative to prior art processes. Systems of the inventiveprocess provide reduced water consumption by at least two differentmethods. In some embodiments, the lack of a rectifier (which representsa major source of water loss in prior art systems) can reduce waterconsumption by systems of the inventive concept by 20% or more comparedto prior art processes. Some water is also lost during processing usingmolecular sieves in prior art processes; such devices are not necessaryin systems and methods of the inventive concept. Water savings producedby recycling of water generated by the ethanol conversion processtypically range from 5% to 15% or more over prior art processes. Withcorn ethanol plants currently producing approximately 15 billion gallonsof ethanol annually, this can reduce the water consumption of plantsutilizing corn fermentation by approximately 4.5 to 6 billion or moregallons a year or more annually via water generation during the ethanolconversion process, and by approximately 11.3 to 20 billion gallons ormore of water a year annually when savings due to the lack of rectifiersare included.

It should be apparent to those skilled in the art that many moremodifications besides those already described are possible withoutdeparting from the inventive concepts herein. The inventive subjectmatter, therefore, is not to be restricted except in the spirit of theappended claims. Moreover, in interpreting both the specification andthe claims, all terms should be interpreted in the broadest possiblemanner consistent with the context. In particular, the terms “comprises”and “comprising” should be interpreted as referring to elements,components, or steps in a non-exclusive manner, indicating that thereferenced elements, components, or steps may be present, or utilized,or combined with other elements, components, or steps that are notexpressly referenced. Where the specification claims refers to at leastone of something selected from the group consisting of A, B, C . . . andN, the text should be interpreted as requiring only one element from thegroup, not A plus N, or B plus N, etc.

What is claimed is:
 1. A method for producing a hydrocarbon product,comprising: applying an alcohol broth at a first temperature to aprimary beer column pre-heater to heat the alcohol broth to a secondtemperature, wherein the second temperature is higher than the firsttemperature, wherein the alcohol broth comprises one or more alcoholsselected from the group consisting of methanol, ethanol, propanol, andbutanol; transferring the alcohol broth at the second temperature to abeer column, wherein the beer column is configured to produce a firstintermediate product stream comprising an alcohol/water mixture and asecond intermediate product stream comprising residual matter; directingthe first intermediate product stream to a reactor pre-heater to producea pre-heated first intermediate product stream having a temperature ofat least 220° C.; directing the pre-heated first intermediate productstream to a furnace to produce a heated first intermediate productstream having a temperature of at least 250° C.; directing the heatedfirst intermediate product stream to a catalytic reactor to generate athird intermediate product stream comprising a hydrocarbon product,water, and a light hydrocarbon fraction; directing the thirdintermediate product stream to a phase separator along a heat transferroute, wherein the heat transfer route is configured to transfer atleast a portion of heat energy of the third intermediate product streamto the reactor pre-heater; separating, in the phase separator, the thirdintermediate product stream into a hydrocarbon product stream comprisingthe hydrocarbon product, a water stream, and a light hydrocarbonfraction stream and optionally directing at least a portion of the lighthydrocarbon fraction stream to the furnace for use as a fuel; andcollecting the hydrocarbon product; wherein the furnace is configured toreceive heat transferred from the catalytic reactor and from combustionof a fuel comprising the light hydrocarbon fraction, and wherein acombination of heat transfer from the catalytic unit and combustion ofthe light hydrocarbon fraction provides at least 30% of thermal energyneeds of the method.
 2. The method of claim 1, wherein the hydrocarbonproduct is selected from the group consisting of gasoline, diesel fuel,jet fuel, chemicals, and a BTX product.
 3. The method of claim 1,comprising the further step of providing a natural gas fuel to thefurnace.
 4. The method of claim 1, wherein the heat transfer route isfurther configured to transfer heat from the third intermediate productstream to the primary beer column pre-heater.
 5. The method of claim 1,further comprising the step of passing the alcohol broth at the firsttemperature through a preliminary beer column pre-heater prior totransfer to the primary beer column pre-heater to heat the alcohol brothto an intermediate temperature.
 6. The method of claim 5, wherein theheat transfer route is configured to transfer heat from the thirdintermediate product stream to the preliminary beer column pre-heater.7. The method of claim 1, wherein energy supplied to the method in theproduction of a volume of the hydrocarbon product represents less than20% of energy obtained on combustion of the volume of the hydrocarbonproduct.
 8. The method of claim 1, wherein the water stream is providedto a fermentation process.
 9. The method of claim 1, wherein at least aportion of the second intermediate process stream is returned to thebeer column.
 10. A method for reducing water consumption in a fuel plantcomprising; providing an alcohol broth comprising an alcohol, whereinthe alcohol broth comprises one or more alcohols selected from the groupconsisting of methanol, ethanol, propanol, and butanol; transferring thealcohol broth at a first temperature to a primary beer column pre-heaterand heating the alcohol broth to heat the alcohol broth to a secondtemperature, wherein the second temperature is higher than the firsttemperature; transferring the heated alcohol broth from the primary beercolumn pre-heater to a beer column that is in fluid communication withthe primary beer column pre-heater; generating, using the beer column, afirst intermediate product stream comprising a concentratedalcohol/water mixture; transferring the concentrated alcohol/watermixture to a catalytic unit pre-heater that is in fluid communicationwith the beer column; generating, using the catalytic unit pre-heater, apre-heated alcohol/water mixture; transferring the pre-heatedalcohol/water mixture to an oven that is in fluid communication with thecatalytic unit pre-heater; generating, in the oven, a heatedalcohol/water mixture; transferring the heated alcohol/water mixture toa catalytic unit that is in fluid communication with the oven;generating, in the catalytic unit, a second intermediate product streamcomprising water, a hydrocarbon product, and a light hydrocarbonfraction; transferring the second intermediate product stream from thecatalytic unit to a phase separator that is in fluid communication withthe catalytic unit; separating, in the phase separator, the secondintermediate product stream into a first water stream and a hydrocarbonproduct stream; and recycling at least part of the first water streaminto at least one of a fermentation process or a fuel generationprocess, wherein the oven is configured to receive heat transferred fromthe catalytic unit and by combustion of a fuel comprising the lighthydrocarbon fraction, and wherein combustion of the light hydrocarbonfraction in combination with heat transferred from the catalytic unitprovides at least 30% of thermal energy needs of the method.
 11. Themethod of claim 10, comprising the additional step of cooling the firstwater stream to generate a second water stream.
 12. The method of claim11, wherein the temperature of the second water stream is at least 30°C. lower than the temperature of the first water stream.
 13. The methodof claim 11, wherein the first water stream is cooled using a radiator.14. The method of claim 11, wherein the first water stream is cooledusing an absorption cooler.
 15. The method of claim 14, where at leastpart of the energy requirement of the absorption cooler is supplied byheat transferred from the second intermediate product stream.
 16. Themethod of claim 10, wherein the second intermediate product streamfurther comprises a light hydrocarbon fraction.
 17. The method of claim16, further comprising the step of separating, in the phase separator,the light hydrocarbon fraction from the first water stream and thehydrocarbon stream to generate a light hydrocarbon stream.
 18. Themethod of claim 17, wherein at least a portion of the light hydrocarbonstream is utilized as fuel for the furnace.
 19. The method of claim 10,wherein the catalytic unit generates at least one mole of water forevery mole of alcohol that is converted to hydrocarbon.
 20. The methodof claim 10, further comprising the steps of: providing a preliminarybeer column pre-heater interposed between a source of alcohol broth andthe primary beer column pre-heater, wherein the secondary beer columnpre-heater is in fluid communication with the primary beer columnpre-heater and the source of alcohol broth; transferring the alcoholbroth at the first temperature to the secondary beer column pre-heater,thereby heating the alcohol broth to an intermediate temperature; and,transferring the alcohol broth at the intermediate temperature from thepreliminary beer column pre-heater to the primary beer columnpre-heater.
 21. The method of claim 20, wherein at least part of theenergy requirement of the preliminary beer column-pre-heater is met bytransferring heat from the first water stream, thereby reducing thetemperature of the hot water stream.
 22. The method of claim 20, whereinat least part of the energy requirement of the preliminary beer columnpre-heater is met by transferring heat from both the first water streamand the second intermediate product, thereby reducing the temperature ofthe first water stream.